<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        * {
            padding: 0;
            margin: 0;
        }

        .top_wrap {
            height: 30px;
            padding: 30px;
            background-color: #4285f4;
        }

     /*   .top {
            width: 100%;
        }*/
    </style>
</head>
<body>
<div class="top_wrap">
    <div class="top">欢迎来到我网站</div>
</div>
</body>
</html>